The geometrical effects in a model coupled with microstructural evolution and mechanical behavior for small-scale solder joints
The effects of stress,size,geometry,and composition on the microstructure in small-scale Sn-Pb solder joints are investigated by using a model coupled with microstructural evolution and mechanical behavior.The growth of both the Pb-rich phase and the Sn-rich phase along the boundaries of the solder joints is observed under an external shear stress and boundary constraints on diffusion.This result indicates that the microstructure in small-scaled solder joints is sensitive to stress.In addition,the heterogeneity of microstructure tends to increase with the shrinking of solder joint size.In particular,the size of the Sn-rich phase is observed to be nearly 1/5 of the standoff height in the solder joint with 1.5 μm pad size.The size effect on the microstructural heterogeneity is more pronounced in the hourglass-shaped joints than in the barrel-shaped counterparts.Furthermore,a larger volume fraction of the well-connected Sn-rich phase is found in the solder joints of a higher content of Sn.The heterogeneous microstructures exert influences on the stress distribution in the joints because the stress concentrates in the Sn-rich phase.The correlation between stress and microstructure is stronger in the hourglass geometry.
Hua Xiong Zhiheng Huang Dong Wu Yong Zhang
School of Physics and Engineering,Sun Yat-sen University,135 West Xingang Road,Guangzhou 510275,China
国际会议
桂林
英文
324-329
2012-08-13（万方平台首次上网日期，不代表论文的发表时间）